Reference Manual


arp - interact with the ARP table

arping - list all machines on a network
arp    [ifn | ip]
arping  ifn [ip | mac]
arpingn ifn [ip | mac]


Command arp extracts information from the ARP table and formats it in a readable form. Each line of output contains information about a single ARP entry and shows the ARP entry state (RESOLVED, REFUSE or PENDING), protocol address (IP address), hardware address (Ethernet address), hardware type, protocol type, interface number, and time to live (in seconds). Permanent entries have an infinite ttl denoted by [+] in the listing.

Argument ifn or ip specifies that only entries with a matching interface number or IP address be displayed.

Command arping lists all machines on a specified network. Command arpingn also resolves IP addresses to names.

The REFUSE state deserves special mention because it allows traffic to be blocked at the MAC level until the time to live of the entry has expired.

If an IP address is specified and no matching entry exists, then one attempt is made to resolve the address. If successful, the ARP cache is updated.